The present invention relates to a sintered carbonitride alloy having titanium as the main component and intended preferably for metal cutting applications.
Titanium-based carbonitride alloys, usually named cermets, are well established as cutting tool material often used for finishing at high cutting speed. More recently, the area of application has been widened toward more toughness demanding applications which has been made possible by, i.e., increased binder phase and nitride contents in these alloys compared to tungsten-based, more brittle hard materials. Another way of obtaining increased toughness is disclosed in U.S. Pat. No. 5,137,565 in which extremely fine-grained alloys are made using melt metallurgically-made intermetallic pre-alloys.
During sintering of titanium-based carbonitride alloys, a solution-precipitation process takes place. As a result, a very common structure in such alloys is hard constituent grains with a core-rim structure. An early patent in this area is U.S. Pat. No. 3,971,656, hereby incorporated by reference, discloses Ti- and N-rich cores and rims rich in Mo, W and C. By a suitable combination of core-rim-structures in well-balanced proportions, optimal properties regarding wear resistance, toughness behavior and/or-plastic deformation can be obtained as disclosed in U.S. patent application Ser. No. 07/543,474, hereby incorporated by reference.
U.S. patent application Ser. No. 07/878,984, hereby incorporated by reference, discloses a titanium-based carbonitride alloy with coarse grains with core-rim structure in a more fine-grained matrix.
EP 447,388 and EP 464,396 disclose manufacturing of carbonitrides directly by carbonitriding of the oxides of the metals or the metals themselves.